Combination evaporator and radiant heater defrost means



Q 21, 1967 G. F. DODGE m, ETAL 3,353,368

COMBINATION EVAPORATOR AND RADIANT HEATER DEFROST MEANS Filed Nov. 12, 1965 INVENTORS GERALD F. DODGE'HI yu/EL F'IG.|

A. ELLlOTT THEKR ATTORNEY United States Patent 3,353,368 COMBINATION EVAPORATOR AND RADIANT HEATER DEFROST MEANS Gerald F. Dodge III and Marvel A. Elliott, Louisville,

Ky., assignors to General Electric Corporation, a corporation of New York Filed Nov. 12, 1965, Ser. No. 507,352 4 Claims. (Cl. 62-276) ABSTRACT OF THE DISCLOSURE A vertical finned evaporator having a radiant heat defrost heated below and spaced from the evaporator includes flanges on the fins about the heater which prevent defrost water from dropping from the fins onto the heater.

The present invention relates to household refrigerators and is more particularly concerned with an improved combination evaporator and radiant heat defrost means for such refrigerators.

Many modern domestic refrigerators include a fin-on tube evaporator which normally operates at below freezing temperatures so that a layer of frost builds up on the surfaces thereof. In order to prevent this layer of frost from bridging or restricting the air passages between the fins and thus materially affecting the efliciency of the evaporator, it is necessary to provide heating means for periodically warming the evaporator to defrosting temperatures.

A known means for quickly defrosting a fin-on-tube type refrigerator evaporator comprises a high temperature concentrated heat source, such as a radiatn heater, located below the evaporator so that the evaporator is warmed by both radiant and convection heating. One suitable type of radiant heater comprises a coil of heater wire enclosed within a heat resistant and electrically insulating quartz or similar tube. As such heaters operate at elevated temperatures above the boiling point of water, all of the evaporator surfaces are quickly warmed to defrost temperatures. By positioning the evaporator so that the fins extend in a vertical direction, the resultant defrost water drains from the fins surfaces for disposal through suitable drain means. However, if any of the defrost water is allowed to come into direct contact with the exterior surface of the heater, the Water will boil violently and produce undesirable and disturbing noises during the defrost cycle operation of the refrigerator.

The present invention has as its principal object the provision of a fin design adapted to prevent defrost water from falling on the heater.

A more specific object of the invention is to provide a vertical fin-on-tube evaporator and in combination there with the radiant heat defrost means positioned below the evaporator, the fin components of the evaporator being so formed as to deflect defrost water draining therefrom away from direct contact with the heater surfaces.

Further objects and advantages of the invention will become apparent as the following description proceeds and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and forming part of this specification.

In accordance with the present invention, there is provided a combination refrigerant evaporator and radiant heat defrost means in which the evaporator comprises a fin structure composed of a plurality of spaced, vertically extending plate-like fins and is normally operable at frost collecting temperatures. Means in the form of a radiant heater having an operating surface temperature above the boiling point of water is provided for periodically and quickly warming the evaporator to defrosting temperatures. This heater is positioned below the evaporator so that the evaporator is warmed to defrosting temperatures by both radiant and convection heating. The fins are formed to include integral flnage portions designed to defleet the defrost water away from the heater and thereby prevent it from coming into direct contact with the heater surfaces. In accordance with what is presently considered to be a preferred embodiment of the invention, the lower edge of each fin is provided with a flanged inverted V- shaped cutout directly above the heater and a sloping flange lanced from the fin above the cutout portion and extending outwardly from the opposite side of the fin from the V cutout flange. By this arrangement defrost water draining from both surfaces of each fin is prevented from dropping onto the heater.

For a better understanding of the invention reference may be had to the accompanying drawing in which:

FIGURE 1 is a vertical side sectional view of a portion of a household refrigerator embodying the present invention;

FIGURE 2 is a perspective view of a portion of the evaporator structure of the present invention; and

FIGURE 3 is a sectional view of one of the fins of the evaporator structure of F GURE 2 taken generally along line 3-3 thereof.

With reference to the drawing, there is shown a refrigerator cabinet comprising insulated walls defining a freezer compartment 1 maintained at a desired freezing temperature by means of an evaporator 2 contained within a housing 3 disposed in the rear portion of the freezer compartrnent 1. The refrigerator also includes refrigerant condensing means including a compressor 4 positioned in a machinery compartment 5 at the bottom of the cabinet and a condenser (not shown) for supplying condensed refrigerant to the evaporator 2 during normal operation of the refrigerator.

The illustrated evaporator 2 comprises a plurality of parallel, horizontally extending refrigerant passes 6 series connected by means of return bends 7 and a fin structure comprising a plurality of parallel vertically extending plate-type fins 8 threaded onto the passes 6 and extending transversely thereto and in spaced relationship with one another. During normal cooling operation of the refrigerator, air from the freezer compartment 1 is drawn into the housing 3 through an air inlet 19 by means of a fan 11 and after passing upwardly through the evaporator 2 is discharged through an air outlet 12 into the freezer compartment 1. It will be understood that the same evaporator, by suitable additional air circulating means, may also be employed to maintain a fresh food storage compartment forming part of the same refrigerator structure at desired storage temperatures.

During normal or cooling operation, the evaporator operates at below freezing temperatures by evaporation of the refrigerant circulated through the passes. As a result, any moisture in the air circulating through the housing 3 condenses and collects as a layer of frost 0n the surfaces of the evaporator structure and particularly on the surfaces of the fins 8. In order to prevent the collected frost from clogging the air passages between the spaced fins, it is necessary to periodically remove this frost layer.

For this purpose there is provided defrost means in the form of a heater 14 positioned below the evaporator, that is adjacent the lower edge 15 of the fin structure and extending transversely thereof. In the illustrated embodiment of the invention, this radiant heater 14 comprises a tube 16 of quartz or the like containing a resistance heater 17 and adapted to operate at radiant heating temperatures which are above the boiling point of water. Preferably the ends of this heater extend through the opposed side walls of the housing 3 in order to provide readily accessible means for connecting the heater to a source of electrical power. When the heater is energized,

the passes 6 and fins 8 are warmed to defrosting temperatures both by radiant heat and by convection heat. This results in a relatively fast melting of the frost layer on the evaporator surfaces. The resultant defrost water flows downwardly along the opposed surfaces of the fins 8 and into a drain trough 18 at the bottom of housing 3. A suitable drain tube 19 discharges the Water into a drain pan (not shown) positioned in the machinery compartment where it is warmed by the compressor and disposed of by evaporation.

In order to prevent any of the defrost water from contacting the hot heater surfaces, each of the fins 8 is formed to include water deflecting flanges so positioned as to divert defrost water flowing down the surfaces to one side or the other of the heater 14.

In the illustrated embodiment of the invention, the defrost diverting means includes a V-shaped flange 21 defining an inverted V-shaped cutout 22 immediately above the heater 14, the flange 21 extending outwardly from one side of the fin 8 to prevent the Water flowing down this side of the fin from falling int-o the space below the flange, that is into the space occupied by the heater 14. For the purpose of deflecting defrost Water flowing down the opposite or reverse side of the flange 8 from coming into contact with the surfaces of the heater 14 there is also provided a slanting flange 23 lanced from the fin stock and extending from the opposite or reverse side of each of the fins 8 above the space occupied by the heater 14 so as to divert defrost water flowing down the reverse side of each fin 8 to one side of the heater 14.

The action of this fin design including the flanges 21 and 23 is to divert the defrost water flow from the entire evaporator area above the heater 14 away from the heater thereby preventing any rapid boiling or sputtering noise which would result if any of the defrost water were allowed to contact the heater 14.

If desired, the fin surfaces may also be treated with a suitable wetting agent which will promote wetting of the surfaces by the defrost Water. As a result, the water will flow down the fin surfaces as a uniform film instead of in droplet or slug form with the result that the flanges 21 and 23 can more readily divert the film flow to one side or the other of the heater 14.

While a double flange structure in which each of the fins comprises flanges struck or formed on opposite sides thereof is preferred, it will be obvious that other flange constructions may be employed to accomplish the purposes of the present invention. For example, each of the fins may include a single flange struck from one surface thereof, the fins being spaced close enough together so the extending edges of these flanges will contact an adjacent fin surface or in other words bridge the space between the fins whereby each flange will serve to divert the water from opposed surfaces of the adjacent fins away from the heater 14.

Therefore, while there has been shown and specifically described what is presently considered to be a preferred embodiment of the invention, it is to be understood that it is not limited thereto and it is intended by the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. In combination, a refrigerant evaporator comprising a fin structure including a plurality of spaced, vertically extending plate-like fins and normally operable at frost collecting temperatures,

a radiant heat defrost heater operable at a surface temperature above the boiling point of water,

said heater being positioned below and spaced from said evaporator for periodically warming said evaporator to defrost temperatures,

said fins being formed to include protective slanting flangeportions above said heater for preventing defrost water draining from said fins from contacting said heater.

2. The combination of claim 1 in which said fins include flanged inverted V-shaped notches above said heater.

3. The combination of claim 1 in which each of said fins include a first protective flange extending from one side thereof and a second protective flange extending from the other side thereof.

4. The combination of claim 1 in which each of said fins include an inverted V-shaped flange adjacent the lower edge thereof and extending from one face thereof and a slanting flange above said V-shaped flange and extending from the other face thereof.

MEYER PERLIN, Primary Examiner. 

1. IN COMBINATION, A REFRIGERANT EVAPORATOR COMPRISING A FIN STRUCTURE INCLUDING A PLURALITY OF SPACED, VERTICALLY EXTENDING PLATE-LIKE FINS AND NORMALLY OPERABLE AT FROST COLLECTING TEMPERATURES, A RADIANT HEAT DEFROST HEATER OPERABLE AT A SURFACE TEMPERATURE ABOVE THE BOILING POINT OF WATER, SAID HEATER BEING POSITIONED BELOW AND SPACED FROM SAID EVAPORATOR FOR PERIODICALLY WARMING SAID EVAPORATOR TO DEFROST TEMPERATURES, 